In the past, solar concentrators have typically been configured to produce either a point focus or a line focus for the impinging solar rays. Line focus concentrators are in the form of an elongated trough, with the line focus basically being in a plane which includes the opposing longitudinal edges of the trough. Point focus concentrators, on the other hand, have been dish-shaped, typically parabolic in cross-section.
At the focal point of the point focus concentrators will typically be either a boiler assembly, in which a selected liquid is heated to high temperatures by the solar rays reflected and focused from the surface of the concentrator or, in some cases, a solar cell assembly, such as shown in U.S. Pat. No. 5,269,851, which is assigned to the assignee of the present invention, the contents of which are hereby incorporated by reference. Typically, such concentrators have a concentration ratio in the range of 500:1, which may be increased somewhat by the use of a prefilter/secondary concentrator positioned in front of the solar cells, which adds an additional focusing capability for the concentrator and has the further benefit of removing some of the heat from the solar cells when liquid is moved therethrough.
While the above-described concentrator structure certainly has some advantages over other solar energy systems in efficiency and cost, it is desirable that efficiency be still further increased, so as to make solar energy competitive with other forms of energy, particularly petroleum. In addition, the primary concentrator portions of solar concentrator systems have usually required "optical quality" finishes for their reflective surfaces to maintain system efficiency. Such optical-quality finishes contribute significantly to the expense of such concentrator systems.